Region-based weighted prediction for coding video with local brightness variations

This paper presents a new region-based scheme for the estimation of weighted prediction (WP) parameter sets for encoders of the H.264/MPEG-4 AVC standard. The proposed scheme is specifically designed for handling local brightness variations (LBVs) in video scenes. It is achieved by making use of multiple WP parameter sets for various regions and assigning them to the same reference frame. An accurate estimation of multiple WP parameter sets is accomplished by: 1) partitioning regions with a simple WP parameter estimator; 2) selecting regions where WP should be applied; and 3) estimating accurate WP parameter sets with a quasioptimal WP parameter estimator. The multiple WP parameter sets of different regions are encoded using the framework of multiple reference frames in the H.264/MPEG-4 AVC standard. With this arrangement, the proposed scheme is compliant with the H.264/MPEG-4 AVC standard. To reduce the implementation cost, a reduction of the memory requirement is realized via look-up tables (LUTs). Experimental results show that the region-based scheme can efficiently handle scenes with global and LBVs and achieve significant coding gain over other WP schemes. Furthermore, our scheme with LUTs can reduce the memory requirement by about 80% while keeping the same coding efficiency as that without LUTs.